We revisit the photo-absorption sum rule for real Compton scattering from theproton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sumrule appropriate at low energies, we propose a new "constituent quark model"sum rule that relates the integrated strength of hadronic resonances to thescattering amplitude on constituent quarks. We study the constituent quarkmodel sum rule for several nuclear targets. In addition we extract the$\alpha=0$ pole contribution for both proton and nuclei. Using the modern highenergy proton data we find that the $\alpha=0$ pole contribution differssignificantly from the Thomson term, in contrast with the original findings byDamashek and Gilman.
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